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Thread: TKO 600 vs T56 Magnum

  1. #1
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    TKO 600 vs T56 Magnum

    Question for you guys. I guess it's in the title of the post. I want to start my build soon and I want to know the difference. I kind of like the idea of a 6 speed, but...

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    Senior Member Avalanche325's Avatar
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    As you know the TKO 500/600 is a 5 speed, made by Tremec. 5th is overdrive. Multiple shifter locations can be done.

    T56 is a six speed, made by Borg Warner. 5th and 6th are overdrive. The T-56 is longer and therefore only works with IRS.

  3. #3
    Not a waxer Jeff Kleiner's Avatar
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    IMHO there really is not a need for a 6 speed.

    Jeff

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    Senior Member edwardb's Avatar
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    Have completed a couple builds with the TKO600 and my Coupe build has the T-56. So familiar with both. By all accounts, the T-56 shifts better. My limited experience with the T-56 so far (shop time plus grand total of two miles) would seem to confirm that. Short and crisp throws. The T-56 is fatter and longer. For a Roadster, only recommended with IRS due to the added length and resulting short driveshaft. Plus with a Roadster you'll like be forced to relocate the e-brake handle. T-56 is more expensive. T-56 has a solenoid lockout for reverse. So that must be addressed. Common solutions are a manual control (e.g. button on the shifter or something similar), connecting in parallel with the brake light switch, or a speed sensitive module that only allows it to go into reverse when not in motion. Which is what I did in my Coupe. The T-56 has a completely different bell housing layout, so check for availability with whatever engine you're planning. Finally, in addition to the added overdrive, the other four gears are somewhat different ratios than the TKO. So you'll want to do the math on those to determine the best diff ratio.
    Last edited by edwardb; 11-07-2019 at 06:22 PM.
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    Senior Member edwardb's Avatar
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    Quote Originally Posted by Avalanche325 View Post
    As you know the TKO 500/600 is a 5 speed, made by Tremec. 5th is overdrive. Multiple shifter locations can be done.

    T56 is a six speed, made by Borg Warner. 5th and 6th are overdrive. The T-56 is longer and therefore only works with IRS.
    Both TKO and T-56 are Tremec. Real early T-56's were Borg-Warner. But was sold to Tremec 20 years or so ago.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
    Build 2: Mk4 Roadster #7750. Sold 04/10/2017. #7750 Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. 03 of 20. 2015 crate Coyote, 2015 IRS. Legal 04/18/2017. #8674 Build Thread and Video
    Build 4: Gen 3 Type 65 Coupe #59. Gen 3 crate Coyote. Delivered 12/2/2017. #59 Coupe Build Thread

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    Paul, you are the reason why I'm looking at the T-56. I was reading your Coup build and saw that was what you were using. You got me thinking, but I think I will stick with the TKO600. Thank you for your input. I can always count on you for sound advise.

    Rod

  9. #7

    Steve >> aka: GoDadGo
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    Rod,

    What car are you planning to build and what is your preferred power plant?
    If you want to come over to the Dark Side there is another 6-Speed Option.

    Steve
    Last edited by GoDadGo; 11-08-2019 at 12:31 PM.

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    Tremec has a new 6-speed, the TR-3160, smaller, shorter and lighter but not sure if it's available for the aftermarket. Saw it on display last November at Tremec. Lower torque rating, 450 something, than the T-56 series.

    In the TKO-600 trans you have the option of a .82 OD generally indicated as the road race version and a .64 OD, the street version. In the T-56 you get both for a $$, weight & length upcharge.

    I have a TKO-600 but planning on changing to a T-56 Magnum for my IRS Challenge Car. Gearing and shifting are the primary reasons.

    Jim

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  12. #9
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    Quote Originally Posted by GoDadGo View Post
    Rod,

    What car are you planning to build and what is your preferred power plant?
    If you want to come over to the Dark Side their is another 6-Speed Option.

    Steve
    Hey Steve,

    I will be building a MK4 with a 427 aluminum sbf around 600 hp & 540lb torque. IRS 3.35 or 3.73.
    No no no, I will not come over to the other side. LOL.

    Rod

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    Quote Originally Posted by Jim1855 View Post
    Tremec has a new 6-speed, the TR-3160, smaller, shorter and lighter but not sure if it's available for the aftermarket. Saw it on display last November at Tremec. Lower torque rating, 450 something, than the T-56 series.

    In the TKO-600 trans you have the option of a .82 OD generally indicated as the road race version and a .64 OD, the street version. In the T-56 you get both for a $$, weight & length upcharge.

    I have a TKO-600 but planning on changing to a T-56 Magnum for my IRS Challenge Car. Gearing and shifting are the primary reasons.

    Jim
    Hey Jim,

    I found it for sale, but it is $4k. I wonder if it will fit in the roadster. It sounds like a great tranny.

    Rod

  14. #11
    Senior Member CraigS's Avatar
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    A comment on your engine diff ratio. W/ that much HP and TQ I'd be looking at a 331 or 315 diff. I have at least 100 less of both in my 408 and the 315 works very well w/ my TKO500.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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    Quote Originally Posted by edwardb View Post

    By all accounts, the T-56 shifts better. My limited experience with the T-56 so far (shop time plus grand total of two miles) would seem to confirm that. Short and crisp throws. The T-56 is fatter and longer.
    All of edwards' info is correct.

    Here is a great video on why exactly T5 / T56 / TR6060 / etc, shift better than top loader / T10 / TKO / etc - the difference is synchro design - the first 9 minutes are conventional synchro operation, the last 6 minutes deal with the newer synchro design and the differences.

    https://www.youtube.com/watch?v=MXsRfbOiBhE

    Quote Originally Posted by CraigS View Post
    A comment on your engine diff ratio. W/ that much HP and TQ I'd be looking at a 331 or 315 diff. I have at least 100 less of both in my 408 and the 315 works very well w/ my TKO500.
    +1

    A 3.55 gear will have you spinning the tires at half throttle in third gear on 200tw tires - it may sound like fun, but it's liable to be the death of you.


    500hp / 500ftlbs / T56 here - started with 3.55 gear, changed to 3.15 - much happier, but still dangerous in third gear.



    I often say that my car is no faster to 100 on street tires than it would be with 400 / 400 - it's just more dangerous in third gear.

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    Rod,

    I have an aluminum RDI block, carbureted 427, TKO-600 .064. About 540hp, 530tqe, 440 at the wheels. In it's previous life and different car it used 3.27 gears, Torsen T2, 315/35-17s, I'm running 3.31s in the new car. Started w/ 3.73 gears prior to the change to 3.27s, wasn't any fun unless burnouts are the plan. It would run to 157 in 4th, I didn't shift to 5th on the track and generally ran to 140 at Grattan (a bit of work) and VIR South Track (coasting). It would still do roll-on burnouts in 1st at 2,500 rpm.

    It would cruise at 2,200 rpm 80 mph. Ran 11.8 @ 120 during my first and only time ever on a drag strip with less than the indicated power. If I ever get the Challenge Car completed it will be about 200# lighter than the previous car.

    Listen to CraigS, he is wise in the ways.

    Jim

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    Senior Member rich grsc's Avatar
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    Quote Originally Posted by rezell3d View Post
    Hey Steve,

    I will be building a MK4 with a 427 aluminum sbf around 600 hp & 540lb torque. IRS 3.35 or 3.73.
    No no no, I will not come over to the other side. LOL.

    Rod
    Take the above advice on gear ratio. If you have that HP and Torque, 3:55 or 3:73 are the wrong setup. I would be installing 3:08, 3:15 max.

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    Steve >> aka: GoDadGo
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    Quote Originally Posted by rezell3d View Post
    Hey Steve,

    I will be building a MK4 with a 427 aluminum sbf around 600 hp & 540lb torque. IRS 3.35 or 3.73.
    No no no, I will not come over to the other side. LOL.

    Rod
    Before you Go Down The Blue Oval Path, look at how nice things can fit if you come over to the Dark Side.

    Naked MK-4 Walk Around
    https://youtu.be/_wnHDNgnNqs

    Gel Coat Driver
    https://youtu.be/CaRlqMmKIzk

    This Ford Looking Dark Side LS Might Be An Option Too!

    https://paceperformance.com/i-238424...ve-covers.html

    The distributor on this crazy LS is from a 289-302 Ford.

    Feel The Power of The Dark Side!

    Go-Darth-Go (aka: Steve)
    Last edited by GoDadGo; 11-08-2019 at 09:46 AM.

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  23. #16
    Senior Member edwardb's Avatar
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    A lot of generalized information here IMO. This diff ratio, that diff ratio, etc. To state the obvious, you can't look at diff ratio by itself. It has to be in combination with whatever trans you're planning to use. Plus of course with the HP and torque of the engine involved and the intended use. It can make a big difference. My experience is with a T-5, 3.55 diff, and a warmed up 306. Good combination, worked well. Second build was a TKO600, 3.27 diff, and a 425 - 450 HP 347. Worked OK too, but frankly always felt it was a little "soft" with the 3.27 diff. Even compared to my first build with a less powerful engine. My current Roadster is a TKO600, 3.55 diff, and a 450 HP or so Gen 2 Coyote. It's a perfect combination IMO and wouldn't change a thing. There's a reason the 3.55 diff is probably the most popular with these builds. Even with all the other variables. When I was researching the Coupe build, decided I wanted to try the T-56. Found that with the different gearing it has, with a 3.73 diff, it nearly exactly lines up with the TKO/3.55 combination in my Roadster that I really liked. I use this tool for the evaluations: http://www.tremec.com/calculadora.php. If I had stuck with the conventional wisdom of 3.55 would have been similar to the 3.27 Roadster which I personally didn't like as much. Even worse had I gone to a lower ratio like 3.27. Which might have been suggested since the Coupe has a 500 or so HP Gen 3 Coyote. Not saying that everyone's conclusion will be the same. Just cautioning to look at the entire picture.
    Last edited by edwardb; 11-08-2019 at 12:05 PM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
    Build 2: Mk4 Roadster #7750. Sold 04/10/2017. #7750 Build Thread
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    Build 4: Gen 3 Type 65 Coupe #59. Gen 3 crate Coyote. Delivered 12/2/2017. #59 Coupe Build Thread

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  25. #17
    Senior Member Avalanche325's Avatar
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    Quote Originally Posted by edwardb View Post
    Both TKO and T-56 are Tremec. Real early T-56's were Borg-Warner. But was sold to Tremec 20 years or so ago.
    That's what I get for double checking on the internet.

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    Thank you for all the input guys. That is why I love this forum. I'm in the process of restoring a 1976 Porsche 912E and their forum sucks balls. You ask a question and you might get an answer in a week or two. I think I will build my engine with a little less output. I am still in my design phase of my build so I can change anything I want before I actually start. This will be my second roadster. I wasn't able to finish my first and had to sell it (sold it on here to Dan, Boat737) due to financial hardships. This next one I will finish dammit. I figured I would order my kit in 2020.

    Rod

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    Hey Paul,

    On your 20th Anniversary Edition what was your final drive, a .63 or .82?

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    Quote Originally Posted by edwardb View Post

    Just cautioning to look at the entire picture.
    I agree with that.

    For around town performance drivabilty - I can recommend figuring what you think you ought to run in the 1/8th + 1/4 mile (based on hp/weight), and what redline / rev limiter you want to run (based on engine abuse).

    Are you going to spin a 427W to the same rpm as a Coyote? - Not likely ($).


    Figure the rear gear to "bump" the rev limiter through the lights in 3rd gear in the 1/8th mile.

    Figure the rear gear to "bump" the rev limiter through the lights in 4th gear in the 1/4 mile.


    They should come out close to the same, or at least greatly reduce the span you're looking at.


    I started with a 6500 rev limit for my 10.5:1 393w - figured a 3.55 gear for that.

    If you wound second out and tried "rolling into the throttle" in 3rd - you didn't get far before feathering the throttle due to wheelspin.


    Reduced rev limit to 6000 (why spin it faster when you're already spinning tires at will?) - refigured gear = 3.08 ~ 3.27


    Naturally a lower cubic inch engine that you're going to twist harder is going to require a different gear.

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    Mike, that makes sense. I'm kind of thinking 3.27 with the TKO 600 .63 would be about perfect for me. What do you think?

    Rod

  31. #22

    Steve >> aka: GoDadGo
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    3.27 gears with 26" tall tires and a .63 overdrive will yield 70.40 MPH at 1,875 RPM's.

    69.59 MPH with 25.7" tires.

    Also, Mike223 and I make similar power and have similar set ups.
    Last edited by GoDadGo; 11-08-2019 at 01:59 PM.

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  33. #23
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    3.27 looks about right to me, depending on tires + rev limit.

    The .63 5th is personal preference on a street car - a lot of people (probably most) prefer the .63 in these cars.


    I really enjoy the .84 5th in my T56 and very rarely use the .56 6th.

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    Mike,

    How did the T56 fit in your roadster? Is it a Magnum? I was a little concerned about it, because it's longer and wider.

  35. #25
    Senior Member Avalanche325's Avatar
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    I have a 500hp 347,rev limiter at 6200, TKO 600 road race and 3:31. I am running Nitto NT05s (200TW). The guys are exactly right that you need to consider the whole drivetrain as a system. Matched with what you are going to use the car for.

    I do a little bit of everything, autocross, track days, cruise around town and longer multi-day cruises. It doesn't take a lot of throttle to blaze the tires launching at autocross. A lower rear ratio would be a nightmare. The tight ratios are nice on the track. 5th gear is very usable on backroads and the highway. I could see the the .68 would be good on the interstate to bring the RPMs and noise down a little.

    If you are looking at a TKO, Liberty's Gears has some nice upgrades. Caron fiber lined synchros, shift rail and finger improvements, etc. I upgraded mine and you can definitely shift quicker. It is still not like shifting an e30 BMW. But its a Cobra, harden up!

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  37. #26
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    Quote Originally Posted by rezell3d View Post
    Mike,

    How did the T56 fit in your roadster? Is it a Magnum? I was a little concerned about it, because it's longer and wider.


    Not too bad - much as edward described above, details as I recall:

    1- Had to replace + scoot the bottom out on the bar that the handbrake mounts to.
    2- Eased the engine maybe 5/8"" forward due to bellhousing to passenger side clearance on the diagonal tube near starter (don't go far forward or you'll need custom headers).
    3- Fabricate transmission mount.
    4- CTS-V T56, shortest of the T56s (not a magnum) - had to fabricate output flange (matches IRS differential input flange) because there was not room for a guibo joint (4" crossmember in the way).
    5- CTS-V T56 - mid shift modification.
    6- Fabricated ball mount assembly to use clutch fork + cable rather than concentric hydraulic (personal preference - works "perfect").
    7- Fabricated 10.5" u-joint to u-joint driveshaft with slipjoint (no slip yoke - CTS-V model).

  38. #27
    Senior Member edwardb's Avatar
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    Quote Originally Posted by rezell3d View Post
    hey paul,

    on your 20th anniversary edition what was your final drive, a .63 or .82?
    It's the TKO600 part number TCET5008, which is .63 final drive. It's also the Liberty Gear's modded version, which was mentioned. They're local for me.
    Last edited by edwardb; 11-08-2019 at 04:11 PM.
    Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
    Build 2: Mk4 Roadster #7750. Sold 04/10/2017. #7750 Build Thread
    Build 3: Mk4 Roadster 20th Anniversary #8674. 03 of 20. 2015 crate Coyote, 2015 IRS. Legal 04/18/2017. #8674 Build Thread and Video
    Build 4: Gen 3 Type 65 Coupe #59. Gen 3 crate Coyote. Delivered 12/2/2017. #59 Coupe Build Thread

  39. #28
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    Quote Originally Posted by rezell3d View Post

    I think I will build my engine with a little less output.
    Quote Originally Posted by GoDadGo View Post

    Also, Mike223 and I make similar power and have similar set ups.
    On those thoughts, let me add that GoDad and I have previously discussed this subject offline and concluded we would both have been just as happy (and a little richer) with "pretty hot" 9:1 350/351ci engines.

    Anything beyond that is simply a question of how fast do you want to go and still spin the tires in a "street" car.


    But if we hadn't built "a little too much" we wouldn't know that for certain.

  40. #29
    Senior Member CraigS's Avatar
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    One other thing to keep in mind when looking at diff and top gear ratios is the cam in your engine. Another consider the whole system thought. My 408 is a mild one so I can drive at 13-1400 rpm in 5th no problem. So the .6x (I don't remember the next digit) 5th gear and 315 ratio work fine. W/ you going to a 427 I will caution against much of a cam. A friend has a Roush 427 in his. At the time they offered two versions w/ about a 50 hp difference. His is the higher output version and is a constant pain because it won't run smoothly below 18-1900. So he is constantly easing around in 4th so it is smooth.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  41. #30

    Steve >> aka: GoDadGo
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    Remember to do your math before picking your combo including the HP to Weight Ratio.
    I've got deep gears in the rear with 3.73's, which is fine since my 5th and 6th gears are .75 and .50 overdrives.
    This gets me to 1,750.00 at 70 MPH, but my problem is tire spin in the first three gears and I haven't tried to break them loose in 4th nor will I try.
    You don't need a ton of power to push these things down the road and my drive-ability for was greatly improved with I took duration out when I switch to a roller.
    Again, just do the math and find that sweet spot that you are looking for and remember that as your power goes up, the tire compounds will definitely need to soften accordingly.

    NOTE: Prior to my camshaft swap I couldn't get into 6th gear until about 80 MPH or it would lug, lug, lug.

    ........If you send me your E-Mail address I can send you a plug and play spread sheet that makes the math easy.

    Our MK-4 is a little different because it is powered by a 383 CID Small Block Dart in front of a ZF 6-Speed transmission.

    1. 383 Small Block Dart 10-1 Somewhat Pump Gas Friendly Compression Ratio!
    2. Eagle Internally Balanced Rotating Assembly With 6" H-Beam Rods With Floating Forged Flat Tops.
    3. Dart Iron Eagle 215 CC Heads with 2.05 Intake & 1.60 Exhaust Valves.
    4. Harland Sharp Roller Rockers & Other Go Fast Goodies.
    5. Comp Cam Extreme Energy 288 Hydraulic Roller Tappet Cam
    6. Edelbrock AVS 800 Feeding A Weiand 7530 Team-G Single Plane Manifold.
    7. Schoenfeld IMCA Modified Headers & They Really, Really Fit, But Stuff Had To Move A Bit!
    8. New Old Stock Corvette ZF 6-Speed Transmission With Hydraulic Clutch. (.75 5th & .50 6th Gear Over Drives)
    9. Standard Front End Set Up With Mustang Brakes & Forte’s .75” Sway Bar.
    10. Standard 3 Link Moser Dana 44 (TSD 500) Rear With 3.73 Gears & Explorer Brakes.
    11. The wheelbase has been shortened by .875" to better center the rear wheels within the wheel arches and improve pinion angle adjustment.
    Last edited by GoDadGo; 11-10-2019 at 04:29 PM.

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  43. #31
    Seasoned Citizen NAZ's Avatar
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    There's a lot of smart and experienced folks on this forum and still you will find a variety of opinions, and that's OK. I'll share one with all y'all too. For those that think there is a HP limit that beyond that only spins the tires -- I'll submit to you that you don't have too much power, you have too little suspension. Or more specifically, too little anti-squat built into your rear suspension. If you are messing with rear gearing to temper that tendency to smoke the tires you're using a band-aid approach. By changing the rear to a numerically lower ratio you're reducing torque to a level that your rear tires will hold with the current suspension set-up. But you're also reducing performance. Look at the rear suspension set-up to find the root cause of tire spin.

    I can't just stomp on the throttle in my car and spin the tires from a rolling start, even at 5 MPH. Off the trans brake it will spin some for a short distance but also launches at more than 2-G's doing that. It's torque that initially breaks the tires loose and with the multiplication of torque through the converter and gearing (1.80:1 1st gear & 3.90:1 rear end) my car applies 10,036 pound feet of torque to the 28" diameter tires. My engine makes 800HP and 627 pound feet of torque (W/O power adders) and that's not too much as I also have my anti-squat set at well over 100% so the tires are planted hard into the asphalt.

    So rather than limit yourself on power, look at how to apply that power to the ground more efficiently. More power = more fun.
    33 Hot Rod Super Pro Drag Racer
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    I agree with Craig on the cam. My 427 idles at 900 reasonably well but it's generally set to 1,000, but doesn't drive well until about 1800, really 2,000. Does cruise at 2,200 very nicely. Same cam and internals with Vic Jr. heads, Performer RPM and 670 Street Avenger was much easier to drive at 1,400 rpm. A lot of cam "transgressions" can be remedied/covered-up with a dual plane manifold and smaller carb. At the same time manifold, carb, headers & exhaust and a different tune pulled about 70hp out of the engine (370 to 440) The updates changed the power curve. I apologize if the dyno numbers are a bit off, as I started on a DynoJet and later switched to a Mustang dyno.

    Cam is a custom CompCam at .608/.613 I/E, 240/248 @ .050, 108 lobe centerline, 9.65:1, AFR 225, Vic Jr, ProSystems 780 HP mechanical w/o choke or horn. 1-7/8" headers.

    Given an opportunity to select components I'd look at the potential torque & hp curves, comparing to rpm/speeds from the gearing calculators. Then do some serious soul searching into what you really want and how you'll really drive it. Understand that the manufacturers usually indicate the power output for a 351, if that's the base engine size, working at 427 changes the output/rpm curves. Usually more c.i. can smooth out what would be a stout cam in a smaller motor.

    Big motors rock! How well it works for you depends on how well you can modulate your right foot. Some form of throttle stop will do well as "training wheels" limiting the torque output until you've developed sufficient acclimation.

    Jim

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  47. #33
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    Quote Originally Posted by NAZ View Post

    I can't just stomp on the throttle in my car and spin the tires from a rolling start, even at 5 MPH. Off the trans brake it will spin some for a short distance but also launches at more than 2-G's doing that.
    Would those tires happen to be drag slicks?

    Have you tried that with a ~200tw street tire?

  48. #34
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    Yes Mike, they are M/T version of street legal drag tires, ET Street S/S (not the DOT radial drag slick that's not intended for street use but the honest street tire they make). I also have a set of Toyo Proxes R888 200TW tires that will also hook. You do have to select the correct tire and pressure but you also have to have enough anti-squat to plant them. Want to make a drift machine -- adjust the anti-squat way less than 100% and you can run wide sticky tires and spin them at will.

    Here's a tip for folks interested. If you're running a FFR 3 or 4-link axle, have someone watch your car that seems to easily spin the tires. I expect the rear end squats under acceleration. That's caused when the axle tucks up as it's being forced to unload from the road. Most folks get wrapped around the axle on adjusting their ride height to some standard dimension with no regard to how that affects the suspension components. I suspect there are a bunch of cars out there with a variety of roll steer and anti-squat issues that either go unnoticed or if poor performance is noticed it's blamed on something else.

    The point I'm trying to make is that how a car launches (spin or no spin) can be significantly affected by suspension set-up. Spinning is not winning. If it was simply too much horsepower then you wouldn't see 200 MPH passes on 10.5" tire cars running more than 2000 HP. And all those 840 HP Dodge factory hot rods wouldn't be able to keep the tires stuck to the road. Ain't no such thing as too much HP. There's only as much HP as you can afford.
    33 Hot Rod Super Pro Drag Racer
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  50. #35
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    Quote Originally Posted by NAZ View Post
    Yes Mike, they are M/T version of street legal drag tires, ET Street S/S (not the DOT radial drag slick that's not intended for street use but the honest street tire they make). I also have a set of Toyo Proxes R888 200TW tires that will also hook. You do have to select the correct tire and pressure but you also have to have enough anti-squat to plant them. Want to make a drift machine -- adjust the anti-squat way less than 100% and you can run wide sticky tires and spin them at will.

    Here's a tip for folks interested. If you're running a FFR 3 or 4-link axle, have someone watch your car that seems to easily spin the tires. I expect the rear end squats under acceleration. That's caused when the axle tucks up as it's being forced to unload from the road. Most folks get wrapped around the axle on adjusting their ride height to some standard dimension with no regard to how that affects the suspension components. I suspect there are a bunch of cars out there with a variety of roll steer and anti-squat issues that either go unnoticed or if poor performance is noticed it's blamed on something else.

    The point I'm trying to make is that how a car launches (spin or no spin) can be significantly affected by suspension set-up. Spinning is not winning. If it was simply too much horsepower then you wouldn't see 200 MPH passes on 10.5" tire cars running more than 2000 HP. And all those 840 HP Dodge factory hot rods wouldn't be able to keep the tires stuck to the road. Ain't no such thing as too much HP. There's only as much HP as you can afford.
    I don't particularly disagree with setup and antisquat - but I'm IRS - any antisquat adjustment here requires a portaband + welder for starters unless I'm missing something.


    ET Street S/S: https://mickeythompsontires.com/drag.../et-street-s-s "Proven R2 compound, the same proven compound used on the quickest “drag radials” on the planet provides superior traction at the strip with little or no burnout required"

    R888 Proxes are 100tw - I have used these previously + liked them, but it was a different Cobra kit (and they lasted maybe 5000 miles). Haven't tried them on this car yet.


    The 840hp Dodges come with custom (Demon logo, at a minimum) Nitto NT05R drag radials, launch control, and traction control (and they're still a handful): https://www.roadandtrack.com/new-car...n-first-drive/


    On a sidenote - I figured the difference between my 25.5" tires and your 28" tires = with 28" tires I'd have to change from a 3.15 gear to a 3.48 gear to maintain the same gearing.


    Another sidenote, here's my all time favorite 800hp "street car" - he's got plenty of antisquat built into it (note the launch), lol, runs pretty good for a 156k mile 302 with an E cam (hint - that's not a 302 block): https://www.youtube.com/watch?v=pf_tQkM3CME
    Last edited by mike223; 11-10-2019 at 01:44 PM.

  51. #36
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    Mike, I remember that episode – think I’ve watched every episode at least twice and was so disappointed when Pass Time was canceled. And thanks for correcting me on the R888 tread wear.
    I owned several street cars with IRS and still have two parked in the garage. Never been impressed with IRS except for some specialized uses but they are popular and have proven competitive. I also haven’t messed with the Mustang IRS – I’d left Ford way before those came out. From what I understand about the only traction related adjustments are weight transfer, shocks, and delrin bushing. All the race car chassis I’ve tune were solid axle except some VW based off-road race buggies way back in the 60’s and that was some old technology. So, you guys and gals with IRS – you may not get far with improving traction. I certainly don’t have enough hands-on experience to suggest any mods to the Mustang IRS.
    But for those that have conventional axles there is a lot you can do to Improve performance and don’t think that you are at a disadvantage to the IRS folks. Since most here like going around corners, here’s a short article discussing the merits of IRS vs solid rear axle from a magazine you may be familiar with: https://grassrootsmotorsports.com/ar...d-axle-vs-irs/
    33 Hot Rod Super Pro Drag Racer
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    Oh hell, now you got me rethinking an IRS. I want the best of both worlds.

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    Rod,

    Going to a straight axle would probably simplify your transmission selection. Generally, the T-56 only fits/works with IRS. I think the new TR-3160 is shorter but it still may not be configured for a SBF and when you found it, it was pricey.

    Seems that you have many decisions to work through. Make your lists, check the boxes, be prepared to change. Welcome to the journey that many here have blazed before you.

    Jim

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  55. #39
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    Quote Originally Posted by rezell3d View Post
    Oh hell, now you got me rethinking an IRS. I want the best of both worlds.

    lol, I don't think you can set up that much antisquat and still be set up for, ummm - spirited curves.

    Let me qualify that with "I am certain the 160mph sleeper Mustang in the video is not at all set up for cornering".


    But a straight axle is not a bad choice in these cars - they work very well too - and simplify the builder's life considerably.

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    Quote Originally Posted by rezell3d View Post

    I found it for sale, but it is $4k. I wonder if it will fit in the roadster. It sounds like a great tranny.

    Rod
    Hay Rod,

    Keep in mind even if it did fit, it doesn’t even come close to holding up to your HP/torque specs.

    Kurt
    If everything seems under control, you’re just not going fast enough....

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    MKIV complete kit # 9395 delivered 7/31/18

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